Designing with Native Plants & Our Ecosystem in Mind Christina Pax, Lead Designer Native Landscape Design Center at Adkins Arboretum cpax@adkinsarboretum.org What does a garden designer do? What do we ask our landscapes to do? Functions for Humans Functions for other Earthlings I. American Fringetree, Chionothus americanus River birch, Betula nigra Great blue lobelia, Lobelia siphilitica New Jersey Tea, Ceonothus americanus Summersweet, Clethra alnifolia, Hedge of Virginia Sweetspire, Itea Virginica, at Mt. Cuba Center Evergreen to semi-evergreen foundation planting of Christmas fern (Polystichum acrostichoides), Heuchera ssp., and Hepatica ssp. Oakleaf hydrangea, Hydrangea quercifolia Amsonias (A. hubrechtii and A. tabernaemontana) Yellowwood, Cladrastis kentuckia Rudbeckia; Echinacea; Switchgrass, Panicum virgatum Cardinal lobelia, Lobelia cardinalis Gray dogwood, Cornus racemosa Wild Ginger, Asarum canadense Virginia bluebell, Mertensia virginica II. Native plants are generous and enjoy lots of relationships the foundation of a healthy ecosystem. 1. Native host plants benefit native moths and butterflies Lupinus perennis and Karner Blue butterfly 1
Aristolochia tomentosa and Pipevine swallowtail (Dutchman s Pipe or Virginia Snakeroot) Spicebush swallowtail needs host Sassafras (Sassafras albidum) or Spicebush (Lindera benzoin) Loblolly pine (Pinus taeda) supports Southern pine sphinx and the Elf moths. Q-Name one way that native plants support biodiversity. Q-List at least two host-plant/butterfly relationships A1- A2- With so many insects to feed, why aren t native plants then all eaten away? Predators and parasitoids suppress pest populations more often and more successfully in the presence of a diversity of alternative prey species. This is more easily achieved in suburban landscapes if native plants dominate the first trophic level.. How does diversity of plants create a healthy ecosystem? Can diversity of plants do what we use pesticides to do? Q- With all these insects, why aren t gardens with native plants eaten to smithereens? Q- What s the best way prevent my plants from being eaten to smithereens? 2. The protein-rich insects that feed on native plants (consumers) benefit young birds, turtles, and others (predators) "Nearly all terrestrial birds rear their young on insects, not seeds or berries. The bird nourishes its young with herbivorous insects that have captured the energy stored by plants." Doug Tallamy 2
This co-evolutionary process proceeds slowly. Plants are the backbone of the ecosystem Plants are producers. Insects and other herbivores are consumers. Serious interruption of this cycle will have serious consequences. Tallamy s research on actual landscapes Comparison of native, designed landscapes vs. non-native. Controlled for size of lot, number of plants and also number of species, size of lot, etc. FINDING 1: Much greater insect population on natives, although no greater perception of damage FINDING 2: Many more birds in the native landscapes. What s next? Mt Cuba Center Comparison of straight species vs. cultivars. -number insect visitors? -amount of pollen? Is it OK to use cultivars to support biodiversity? Which kind? What characteristics, if any, reduce wildlife value? 3
Q-Name a second way that native plants support biodiversity. Q-List at least two groups of creatures that feed on native insects. If insects don t like alien plants, why do I see so many bees and butterflies at my butterfly bush? Is this alien plant just as valuable as the native Joe Pye weed? Why or why not? 3. Native plants provide excellent shelter Loblolly pine, Pinus taeda and Persimmon, Diospyros virginiana Tulip tree, Liriodendron tulipifera Fragrant Sumac, Rhus aromatica. Indigo blue buntings. Virginia redcedar, Juniperus virginiana Inkberry, Ilex glabra Winterberry, Ilex verticillata Q-Name two native trees and the kind of shelter they are known to provide. Q-List at least two native shrubs and the creatures that create shelter within them. 4. Native plants provide food for pollinators, such as honeybees Spiderwort, Tradescantia virginiana Common Milkweed, Asclepias syriaca 5. Native plants provide food for migrating insects and birds If birds do also eat the berries of alien plants like autumn olive, multiflora rose, and oriental bittersweet, why shouldn t I plant those species? 4
Alternate-leaf dogwood (B), Cornus alternifolia Elderberry (C), Sambucus canadensis Arrowwood viburnum (D). Viburnum dentatum 6. Gardening with natives reduces the risk of non-natives that are now or could soon become invasive. When non-natives escape into the wild and reproduce aggressively taking full advantage of the lack of predators here to keep them in check they can displace the native vegetation. Pest-free and vigorous alien exotic plants = natural landscape invaders! III. Native plants strengthen our connection to nature Painted box turtle Bluebird nests Q- What type of landscapes feel the most comfortable or inspiring to you? IV. Organizing a native landscape design Meadow Edge Forest Meadow Shorter, esp. close to house Select install & maintenance methods Seeded? Plugs? Gradual conversion method? Mowing, weedwacking, fire? Invasion strategies Wide paths for access and enjoyment Embrace change and unpredictability! 5
Edge Great along paths Transition from lawn to forest Other transitions: height difference gateway Glue for creating drama Forest designed, low maintenance, native forest 1. Trees are planted in groves, not as isolated specimens. 2. Shrubs are encouraged to form colonies. 3. Groundcovers are planted in thick, naturalistic sweeps, not on equi-distant spaced grid, and selected for toughness and ability to suppress weeds. 4. All plants are native and selected to closely match site conditions, especially soil ph, texture, and moisture levels. 5. Small baby trees are tucked within the forest to ensure future canopy. 6. Trees are chosen to have leaves that will decompose quickly* What can a Master Gardener do? 1. Adopt a positive message, focused on positive role each household landscape can play. 2. Pick 5 favorite natives in each category (tree, shrub, perennial) and THOROUGHLY learn about them. When do they bloom, what soil, sun and moisture do they prefer, and what other creatures do they support? 3. Improve your design skills, teach design, share examples of good DESIGN. (not just native species thrown out there!) SOME VERY USEFUL NATIVE TREES AND SHRUBS Betula nigra River birch Carya alba Mockernut hickory Cercis Canadensis Redbud Magnolia virginiana Sweetbay magnolia Quercus alba White oak Quercus bicolor Swamp white oak Juniperus virginiana Eastern redcedar CLAY SAND NOTES Cornus racemosa Photinia pyrifolia Gray (or Red-panicled) dogwood Red chokeberry 6
CLAY SAND NOTES Rhus aromatica Viburnum dentatum Viburnum prunifolium Fragrant sumac Arrowwood viburnum Blackhaw viburnum RESOURCES ONLINE 1. Lady Bird Johnson Wildflower Center wildflower.org/plants 2. USDA Plants Database plants.usda.gov 3. For Piedmont plant lists, see mtcubacenter.org 4. Missouri Botanical Garden s Plant Finder Database missouribotanicalgarden.org/plantfinder NATIVE LANDSCAPE PLANTS For clay and for sandy soils CLAY SAND NOTES Red Maple x x 40-60 h. Regional variances in heat/cold Acer rubrum tolerance. Buy plants grown/sourced within region. River Birch x 40-75 h. Heritage, Duraheat, City Slicker Betula nigra Mockernut Hickory x 75-100 h. Carya alba Redbud x x 20-30 h. Cercis canadensis Sweetbay Magnolia x x 20-30 h (60 coastal). Evergreen Magnolia virginiana cultivars Henry Hicks, (also newer ones) Chlorosis at high ph. London Planetree x x 70-100. Very compaction tolerant. Greater (cross with Am. Sycamore) disease resistance than straight sycamore Platanus x acerifolia (i.e. Anthracnose). White oak x x Unsurpassed wildlife value. Plant small. 7
Quercus alba Swamp white oak x x Easier to transplant. Chlorosis at high ph. Quercus bicolor Red oak x Aurea has yellow leaf Quercus rubra Bald cypress x x Very popular in Europe. 50-100 h. Taxodium distichum Compaction tolerant. All soils except high ph. Atlantic White Cedar x x Very adaptable. Deer candy. 50-75 h, but Thuja occidentalis there are many cultivars for size and shape. Redtwig dogwood x x 8-10 h. Red canes. Many colored cultivars. Cornus sericea Likes to form colony. Gray dogwood x 10-15 h. Berries on red panicles. (red-panicled dogwood) Likes to form colony. Cornus racemosa Witch hazel x x 15-20 h&w. Blooms October. Wonderfully Hamamelis virginiana interesting, scraggly, vase-shaped form. Red Chokeberry x x 8-10 or taller. Takes pruning well. See also Photinia pyrifolia shorter Black chokeberry, Photinia (formerly Aronia arbutifolia) melanocarpa. Sumac family x x Gro-low 2-3 h. R. aromatica straight sp. 6 h. Rhus aromatica, Gro-low, Fragrant sumac R. copallina 20-35 h. All excellent for birds. Rhus copallina, Winged or Shining sumac Arrowwood Viburnum x x 10-15 h. Blue muffin shorter. Many cultivars. Viburnum dentatum Blackhaw Viburnum x x 12-24 h. Edible berries. Great as small tree. Viburnum prunifolium Superb fall color. 8